Glucose utilization by 6pgd genotypes in Lolium perenne

Authors

  • D. RAINEY-FOREMAN,

    Corresponding author
    1. Department of EPO Biology, Campus Box 334, University of Colorado, Boulder, CO 80309-0334, USA
      Department of Biology, Macalester College, 1600 Grand Avenue, St Paul, MN 55105, USA. Fax +1 612 696 6443.
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  • J. B. MITTON

    1. Department of EPO Biology, Campus Box 334, University of Colorado, Boulder, CO 80309-0334, USA
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  • This paper reports some of the results from a larger study of the physiological and demographic sequences of enzyme variation in perennial ryegrass. This work was performed at the University ofColoradowhere Daphne Rainey-Fore man completed her PhD in the laboratory of Jeffry Mitton. After completion of post doctoral work in the study of plant development and molecular biology at UC Berkeley and University of Michigan, she accepted an assistant professor ship at Macalester Collegeinst. Paul, MN. Jeffry Mitton's laboratory p u p is studying the ecological and evolutionary genetics of protein polymorphism and DNA markers in both plants and animals.

Department of Biology, Macalester College, 1600 Grand Avenue, St Paul, MN 55105, USA. Fax +1 612 696 6443.

Abstract

To gain a deeper understanding of the mechanisms underlying associations between allozyme genotypes and rates of respiration in Lolium perenne, Vmax Km and rates of glucose flux through glycolysis and the pentose phosphate pathway were estimated for the three genotypes of the 6pgd locus. Km Vmax and Vmax/Km differed significantly among genotypes. Values of Km for the 11, 12, and 22 genotypes were 0.29, 0.25, 0.13, while the values of Vmax/Km for die 11, 12, and 22 genotypes were 3.79, 3.85, 6.70. Flux through the pentose shunt did not differ among genotypes at 20 °C, but at 35 °C the rates of flux for the 11, 12, and 22 genotypes were 0.15, 0.25 and 0.42, respectively. Thus, the 6PGD allozyme genotypes differ markedly in both enzyme kinetic characteristics and in flux through a metabolic pathway. These associations reveal potentially causal relationships between allozyme genotypes and rates of respiration.

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